JPH0243385A - Electrode for corrosion prevention - Google Patents

Abstract

PURPOSE:To provide the electrode for corrosion prevention which can smoothly dissipate a generated gas to the outside field by positioning the other end of a gas vent pipe which is communicated at one end with the outside near to an insoluble metallic electrode of a bar shape, etc., in which the juncture to a flexible conductor is sealed against the outside. CONSTITUTION:The above-mentioned insoluble electrode 4 is formed by coating the surface of a bar-shaped or pipe-shaped and more particularly a holeless pipe-shaped base body with an electrode active material. Namely, the base body consisting of Ti, Zr, etc., or the alloys thereof is coated with platinum group metals and/or the oxide thereof. the flexible conductor 1 for feeding electricity to said electrode 4 is connected to the base body and, for example, an insulating material is packed around the juncture thereof to prevent short circuiting of the juncture and the leakage of current. The other end of the gas vent pipe 11 which is communicated at one end with the outside is positioned near to the electrode 4. The gas generated on the surfacer of the electrode 4 by energization is guided through said pipe 11 and is released to the outside. As a result, the situation in which the energization is hindered or prohibited by the formation of the gaseous layer is averted.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is applicable to electrodes for corrosion protection of various metals and alloys, particularly for cathodic protection of metals buried in the soil, reinforcing bars and steel frames in concrete, etc. This invention relates to an anticorrosion anode with excellent degassing properties.

(Prior art and its problems) In recent years, instead of using anti-corrosion coatings to prevent the corrosion of metal parts and metal pipes in soil, concrete, etc., electricity has been developed to stabilize the metals to be protected by basely polarizing them. Corrosion prevention methods have been adopted. Cathodic protection can be roughly divided into two types: galvanic protection and cathodic protection.The latter cathodic protection uses an insoluble anode to connect a DC power supply between the metal to be protected and conduct electricity. It stabilizes the metal to be protected by maintaining it in a base state. The cathodic protection has the advantage that the corrosion protection continues as long as the current supply is not stopped, and is widely used despite the disadvantage that it requires large-scale equipment.

In this cathodic protection, if the gas generated on the anode surface is not sufficiently dissipated into the soil, a gas layer will form on the anode surface, making it difficult or impossible to conduct electricity, and causing a voltage increase after short-term use. There is. In order to avoid this, the present inventors have proposed a method in which the electrode is shaped like a perforated pipe to guide the generated gas into the hollow electrode and dissipate it to the outside world, and a method for releasing gas into a backfill material formed around the electrode. proposed a method of forming a space for dispersion and dissipating it to the outside world through the space (Japanese Patent Application No. 9568/1982). However, this method cannot be applied when the electrode is in the shape of a non-porous pipe or rod, or when no backfill material is used.

(Purpose of the Invention) The present invention was made to solve the problem of soft soil, and when a pipe-shaped or rod-shaped electrode that does not use hackfill material is used as a corrosion-proof electrode, the generated gas can be smoothly removed from the outside world. It is an object of the present invention to provide a corrosion-protecting electrode that can avoid a situation where current flow becomes difficult or impossible due to the formation of a gas layer.

(Means for Solving the Problems) The present invention provides an insoluble metal electrode in the vicinity of a rod-shaped or pipe-shaped insoluble metal electrode which is connected to a flexible conductive wire and whose connecting portion is sealed from the outside world, with one end communicating with the outside world. This is an anti-corrosion electrode characterized in that the other end of a degassing pipe is positioned.

The present invention will be explained in detail below.

The insoluble metal electrode in the present invention is formed by coating an electrode active material on a rod-shaped or pipe-shaped, particularly non-porous pipe-shaped substrate. Since the insoluble metal electrode tends to be roughly handled at the installation site, it needs to be made of a material that can withstand such handling and is required to have sufficient corrosion resistance. It is preferable to use valve metals or alloys containing these metals as main components. Examples of the electrode active material include platinum group metals and/or their oxides, such as Pt, Ir, Os, and Pd.
, Ru, Rh, or their oxides, and these have the same robustness as the base metal of the metal electrode and are extremely durable as electrodes, so they can be used instead of conventionally used ferrite. Compared to other electrode materials, it is much more stable and durable.

In the present invention, a flexible conductive wire for supplying power to the insoluble metal electrode is connected to the insoluble metal electrode via an appropriate connection part. The connection needs to be sealed from the outside world, such as soil, to prevent short circuits, current leakage, or damage.

The encapsulation is performed, for example, by filling the periphery of the connection portion with an insulating material.

A gas venting pipe, one end of which communicates with the outside world, is located near the insoluble metal electrode, and the gas generated on the electrode surface by energization is guided to the outside world through the pipe and dissipated. Although the outer end of the pipe may be located anywhere, it is desirable for handling that it be integrated with the conductive wire. The material of the gas venting pipe is preferably a flexible material with good corrosion resistance, such as polyvinyl chloride. Although only one pipe may be installed, preferably a plurality of pipes having different heights at the other end may be installed.

When the insoluble metal electrode is rod-shaped, axial grooves or spiral grooves can be carved on the electrode surface to make gas movement smoother; Gas can be diffused more smoothly by using the pipe-like electrode with small holes and guiding the gas into the electrode as described above.

The present invention will be described in more detail below based on specific examples shown in the accompanying drawings.

The drawing is a longitudinal sectional front view showing a specific example of the anti-corrosion electrode according to the present invention.

A conductive wire 1 extending in the vertical direction is composed of a core wire 2 made by bundling a large number of small-diameter copper wires, aluminum wires, etc., and a flexible insulating material 3 such as synthetic resin coated around the core vA2.
A portion of the insulating material 3 is completely removed in the circumferential direction at the lower end. The lower end of the core wire 2 has a protrusion 5 formed upward at the upper end of the rod-shaped insoluble metal electrode 4.
are tightened with bolts 6 and nuts 7 to form a connection part, and the connection part is housed in a connection case 9 filled with powdered insulating material 8 and opened at the top and fitted onto the upper end of the electrode 4. has been done. A top plate 10 is fitted into the upper opening of the connection case 9.

The other end of the degassing pipe 1), one end of which penetrates the connection case 9 and is integrated with the conductive wire 1, is located close to the longitudinal center of the insoluble metal electrode 4.

When the corrosion-protective electrode of this embodiment having such a configuration is energized from the conductor 1 through the connection part, the insoluble metal electrode 4 functions as an anode to maintain the potential of the metal to be protected at a base level and protect the metal from corrosion. With the energization, gas is generated in the electrode 41, the gas enters the gas venting pipe 1) located nearby, is guided to the outside world by the pipe 1), and a gas layer is formed on the surface of the electrode 4. Prevent it from forming.

If the other end of the degassing pipe 1) is integrated with the conducting wire 1, the pipe 1) can be handled together with the conducting wire 1, which makes it easier to handle the anti-corrosion electrode when the pipe 1) is not included. Its handling does not become complicated.

Next, examples of a corrosion prevention method using the corrosion protection electrode of the present invention will be described, but these examples are not intended to limit the present invention.

(Example 1) A copper conducting wire was connected to the end of an iridium oxide-coated titanium rod-shaped electrode with a diameter of 1 cm and a length of 1)c+* having the shape shown in the figure, and the connected portion was covered with an epoxy resin and a vinyl chloride resin. , one end of a gas venting pipe made of polytetrafluoroethylene is brought close to approximately the center of the rod-shaped electrode, and the other end of the gas venting pipe is passed through the connecting portion to be integrated with the conductive wire, thereby providing protection. It was used as an edible electrode.

(Example 2) In place of the above-mentioned rod-shaped electrode, a rod-shaped electrode with grooves formed along the axial direction to provide gas venting space was used to obtain the same anticorrosion electrode as in Example 1.

(Example 3) In place of the rod-shaped electrode of Example 1, a pipe-shaped electrode having a plurality of fine holes was used to obtain a similar anti-corrosion electrode.

A total of three types of anti-corrosion electrodes mentioned above were installed at a depth of 1.5 m.
An iron pipe with a diameter of 80 mm and a length of 20 m was installed as a counter electrode at a distance of about 10 m from the electrode, and each was connected to a power source to perform a corrosion protection test. The voltage of the electrode is 30V
When the current change and the potential change of the counter electrode were tracked, a current of about IA/dm" was flowing through the electrode base from the beginning, and the counter electrode potential was -0.95 to -0.80V.

In each example, this state continued for about half a year or more without any fluctuation, and it was confirmed that gas degassing was sufficiently performed.

(Effects of the Invention) In the anticorrosion electrode according to the present invention, a current-carrying conductor and an insoluble metal electrode are integrally connected in advance, and the connection portion is sealed from the outside, and one end is provided near the insoluble metal electrode. is located at the other end of the gas venting pipe that communicates with the outside world.

Therefore, firstly, the gas generated at the insoluble metal electrode upon energization smoothly dissipates to the outside world through the degassing pipe, so that a gas layer that makes energization difficult or impossible is formed on the surface of the insoluble metal electrode. This prevents the formation of corrosion, and the corrosion protection of the metal to be protected can be performed in a stable manner for a long period of time.

Second, it improves the durability of the connection parts, which are easily damaged, and thereby extends the life of the entire electrode, significantly reducing the number of times the anti-corrosion electrode, which is buried in soil, must be replaced. This makes it possible to reduce the number of personnel and costs required for maintenance management.

Third, since the insoluble metal electrode and the conductor are integrated and standardized, they can be mass-produced at the factory without any problems with the connections, and can be handled like normal conductors at the construction site. This greatly improves work efficiency, especially on-site.

Fourth, since the conductor wire is flexible, it can be placed in an optimal manner according to the shape of the counter electrode, regardless of the location where it is installed.This allows the anode and cathode to be as close as possible, reducing the resistance between the two electrodes. The applied voltage is also reduced, making it possible to save energy.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional front view showing a specific example of the anti-corrosion electrode according to the present invention. 1... Conductor wire 4... Insoluble metal electrode 9... Connection case 1)... Gas venting pipe

Claims (2)

[Claims] (1) A gas venting pipe, one end of which communicates with the outside world, is placed near a rod-shaped or pipe-shaped insoluble metal electrode that is connected to a flexible conductor and whose connection portion is sealed from the outside world. An anti-corrosion electrode characterized by: (2) The anti-corrosion electrode according to claim 1, wherein one end of the degassing pipe is integrated with a conducting wire.